Coring apparatus



March 9, 1954 Filed NOV. l2. 1948 J. C. STOKES CORING APPARATUS 2 Sheets-Sheet l March 9, 1954 x. c. s'roKEs CORING APPARATUS 2 Sheets-Sheet 2 Filed Nov. 12, 1948 Patented Mar. 9, 1954 ooRlNG ArPAnA'rUs 4 John C. Stokes, Houston, Tex., assignor to Reed Roller Bit Company, Houston, Tex., a corpo-v ration of Texas Application November 12, 1948, Serial No. 59,598

(Cl. Z55- 72) 6 Claims. 1

This invention relates to new and and useful improvements in coi-ing apparatus.

In conventional coring apparatus now in general use, the inner core-receiving barrel is mounted within an outer barrel which, in turn, is attached to the drill pipe and the inner barrel is usually free-floating or rotatable with respect to said outer barrel, whereby the inner barrel may remain stationary to receive the core as the outer barrel and core bit are rotated by the drill pipe during the coring operation. A single core catcher is ordinarily disposed within the core bit and functions to retainAzhe core within the inner barrel during removal of the apparatus from the well bore. Removal, of course, is accomplished by the removal of the entire drill pipe. More recently, diamond core drills have come into use for coring in harder formations and the single core catcher is disposed within said bit so as to retain the core Within thev inner barrel. 'It will be evident that if the single core catcher fails to operate properly, the complete core will not be recovered or in some instances, the entire core may be lost. Further, because reeovery of the core within the inner barrel may be accomplished only by withdrawal of the drill pipe, it will be apparent that if the core bit becomes stuck it becomes impossible to recover the inner barrel' and the core which is disposed therein.

It is, therefore, one object of the present invention to provide an improved coring apparatus which will assure complete recovery of the core which enters the inner barrel during the coring operation.

An important object of the invention is to provide animproved coring apparatus, having a dual core catcher means, whereby in the event one of said catchers fails to operate properly, the core will be retained by the second catcher to thereby assure recovery of said core.

Another object of the invention is to provide an improved coring apparatus which includes a diamond core bit and anv inner core-receiving barrel, together with a core catcher mounted within the core bit and a second catcher mounted within the lower end of the core-receiving barrel, said catchers being so arranged 'that the lower catcher within the bit is adapted to function in advance of the second or upper catcher, whereby so long as said lower catcher operates properly the core is broken oif and retained thereby, the upper catcher remaining inactive until and unless the lower catcher fails to operate.

A further object of the invention is to provide an improved core-taking apparatus, of the character described, wherein the inner core-re ceiving barrel is coupled between the drill pipe and the outer barrel and core bit, with the connection between said inner and outer barrels being such that in the event that the outer barrel and core bit carried by said outer barrel become stuck in the bore hole, the drill pipe and inner barrel may be readily detached therefrom to permit recovery of the core within said inner barrel.

Still another object of the invention is to provide an improved core-taking apparatus, of the character described, which includes a diamond core bit and a rotatable barrel, which barrel is mounted on thrust bearings at its upper portion; said apparatus being so constructed that downward circulation or flushing through the Inner core-receiving barrel may be accomplished prior to the coringoperation, with said core-receiving barrel being adapted to be closed against downward flow therethrough by a ball check valve which may be dropped into position through the drill pipe after the downward circulation or flushing is complete and just prior to the actual coring operation.

'I'he constructiondesigned to carry out the invention Will be hereinafter described together with other features of the invention.

The invention will be more readily understood from a reading of the following specification and by reference to the accompanying drawings. wherein an example of the invention is shown, and wherein:

Figure l is a longitudinal, sectional view of the n Iupper portion of a coring apparatus, constructed in accordance with the invention,

Figure 2 is a continuation of Figure 1 illustrating the lower portion of the apparatus,

Figure 3 is a view, similar to Figure 2, showing the position of the core catchers during the coring operation,

Figure 4 is a horizontal, cross-sectional view, taken on the line 4-4 of Figure 2, and

Figure 5 is a horizontal, cross-sectional view, taken on the line 5 5 of Figure 2.

In the drawings, the numeral I 0 designates the usual drill pipe which has a special coupling Il connected to its lower end. The intermediate portion of the coupling I I has its external diameter reduced and provided with coarse screw threads I2, whereby the upper end of the outer barrel I3 of the core-taking apparatus may be connected to said coupling. A core bit I4 which is illustrated as a diamond core bit, is attached by the usual threaded engagement to the lower end of the outer barrel I3 and thus. when the drill- 3 pipe is rotated, a rotation is imparted to the outer barrel I3 and core bit I4 to perform the usual core drilling.

'I'he special coupling which connects the drill pipe I3 to the outer barrel I 3 is clearly shown in Figure 1 and has its external diameter further reduced below the coarse threads I2 to form a reduced shank portion I3 at the lower portion of the coupling. An axial bore I3 extends entirely through the coupling and may have its lower portion increased as indicated at Ita, whereby an internal annular, shoulder I1 is formed within the bore. Inclined passages or ports I3 extend through the wall of the coupling and establish communication between the bore Il and the interior of the outer barrel I3. Thus, a fluid circulated downwardly through the drill pipe I and bore I3 may pass outwardly through the passages I3 and then downwardly through the outer barrel I3 of the core-taking apparatus.

An inner core-receiving barrel I3 is disposed axially within the outer barrel I3 of the coretaking apparatus and has its upper end connected to the lower portion of a supporting and vent tube 20. The tube 20 may be connected in any suitable manner to the upper end of the inner barrel I3 and as is clearly shown in Figure 1, has its bore communicating with the bore of said inner barrel. The upper portion of the supporting and vent tube 20 extends into the lower portion Ita of the bore of the coupling I| and has a valve seat 2| mounted thereon. As will be explained, a ball valve 22 is adapted to engage the seat 2| to prevent a downward flow through the vent tube and into the bore of the inner barrel I3.

The supporting and vent tube 20, as well as the inner barrel I3 which is connected thereto, is rotatably supported by means of upper and lower ball bearings 23 and 24. The bearings engage an external annular flange 25 which is formed on the tube 20 and said bearings are confined by means of a sleeve-like bearing housing 23 which has its upper end threaded on the reduced shank portion I of the coupling II. Obviously, said bearings not only permit free rotation of the inner barrel but also function as thrust bearings to take longitudinal thrust. Suitable upper and lower packing rings 21 and 23 pack off around the tube 2l) on opposite sides of the bearings 23 and 24. Due to the rotatable mounting of the vent tube and the inner barrel i9 which is connected therewith, it will be apparent that the drill pipe III, coupling II and outer barrel I3 may be rotated to impart rotation to the core bit I4, while the inner barrel I3 may remain stationary.

'Ihe core bit I4 is illustrated as the usual diamond core bit and has an axial bore 23 whereby the core being cut may enter said bore. The intermediate portion of said bore is formed with an inclined or tapered actuating surface 30, whereby a core catcher 3| may be mounted within the bit. The catcher 3| is of usual construction and is generally sleevelike, being provided with a longitudinal slit 32, whereby as the catcher moves downwardly within the tapered actuating surface, its internal diameter is reduced to rmly engage around a core which may be extending therethrough. During the coring operation, the frictional engagement of the core passing upwardly through the catcher 3| will maintain said catcher in an upper or raised position abutting the shoulder |3a formed by the lower end oi the outer barrel I3, as shown in Figure 3 and in such position, the core catcher will be in its expanded or non-gripping position. After coring is complete. an upward movement' of the barrel and core bit will cause the tapered actuating surface 33 within the bit to coact with the outer tapered surface of the core catcher to cause said core catcher to be moved inwardly into its gripping position and thereby break oi! the core which has been cut. It is noted that this type of catcher is of usual construction.

It sometimes occurs. particularly in the harder formations, that the catcher 3| may fail to operate with the result that a full recovery of the core is not had. In order to assure recovery of the core in the event that the lower catcher 3| fails to operate, a second core catcher 33 is provided within the lower end of the inner core barrel I3. The catcher 33 is of the usual spring finger type and is normally disposed within the bore 34 of a tubular extension 35 which is secured to the extreme lower end of the inner core barrel I3 by means of a coupling 3l. The bore 34 of the extension 3l is provided with an inwardly tapered portion 34a and this portion forms an actuating surface which is adapted to coact with the resilient or spring fingers of the core catcher 33, whereby when the catcher 33 is moved downwardly within the tapered portion 34a, the fingers are moved inwardly into tight engagement with the core extending through the catcher. So long as the catcher 33 is in the bore 34 above the tapered portion 34a, the fingers of said catcher are in an expanded or non-gripping position.

As a core is being taken. the frictional engagement of the core with the inner surfaces of the catcher 33 will cause said catcher to move up wardly into the position shown in Figure 3, in which position the upper end of the catcher engages the shoulder 33a formed by the lower end of the coupling element 33. It is noted that the distance between the tapered actuating surface 34a of the bore of the extension 35 and the shoulder 36a is greater than the distance between the tapered actuating surface 3l within the core bit I3 and the shoulder I3a against which the lower catcher 3| will abut when in its upper position. Therefore, during a coring operation, the core which moves upwardly within the core bit and then into the inner barrel will cause the lower catcher 3| to engage its shoulder |3a before the core catcher 33 will engage' its stop shoulder 33a. Thus, the travel of the upper core catcher is greater than the movement or travel of the lower catcher.

After coring is complete and the outer barrel and core bit are moved upwardly, the lower catcher 3| travels a lesser distance before it engages the core than does the upper catcher 33. In other words, the lower catcher 3| will enter the tapered actuating surface 33 of the bit before the upper catcher 33 will coact with its tapered actuating surface 34a within the bore of the tubular extension 35, with the result that the lower catcher will be moved into gripping position prior to the time that the upper catcher will be moved into its gripping position. It the lower catcher 3| functions to grip the core and break said core, then the upper catcher will not function; however, in the event that the lower catcher should fail to operate properly, continued movement of the apparatus with respect to the core will cause the upper catcher 33 to be moved within the tapered portion 34a, whereby said upper catcher is urged into gripping position to iirmly grip and break ot! the core.

In the operation of the device, the parts are assembled as shown in rFigures 1 and 2, and the core-taking apparatus is connected to the drill pipe by means of the special coupling II. If a flushing or circulating operation downwardly through ,the inner barrel I9 is to be accomplished before the coring is carried out, the ball valve 22 is removed from the seat 2| so that the apparatus is lowered into the hole with the vent tube 20 having its .bore open. Upon reaching the lower portion of the bore and before a .coring operation isy carried out, a flushing fluid is circulated downwardly through the drill pipe I0 and this uid will flow downwardly through the vent tube 20 and through the inner barrel I9 to thoroughly cleanse said barrel. After the flushing or downward circulation lof fluid is completed, the ball valve 22 is dropped downwardly through the drill pipe and will engage the seat 2I to close the vent tube 20 and inner barrel against a downward flow. Because the ball valve is downwardly seating, .it will be apparent that said valve may be moved upwardly to allow venting of the inner barrel when the pressure within the barrel exceeds the pressure within the bore of the drill pipe thereabove.

As the coring operation proceeds by. rotating the drill pipe, drilling fluid is circulated downwardly through the drill pipe and passes through the inclined passages I8 and the special coupling lI, and then downwardly through the outer barrel I3 to the vertical fluid passages Ida in the core bit I4. The core which is cut moves upwardly through the bore 29 of the core bit and through the lower catcher 3I and into the extension 35 past the upper catcher 33 and into the inner barrel I9. As the core is being cut and moves upwardly into the barrel I9, its frictional engagement with the core catchers moves safid catchers upwardly against their respective stop shoulders I3a and 36a as shown in Figure 3.4

Also, the frictional engagement of the core within the inner barrel I9 maintains said inner barrel stationary, while the outer barrel and core bit are rotated by means of the drill pipe. Coring continues until a sufficient core has been taken.

When it is desired to retrieve or recover the core, drilling is stopped and the drill pipe and barrel I3, as well as the core bit attached to the lower end of the outer barrel, are moved upwardly. This moves the tapered actuating surface 30 within the core bit upwardly with respect to the lower catcher 3l and also moves the tapered surface 34a upwardly with respect to the upper catcher 33. As explained, the travel of the lower catcher 3I is less than the travel of the upper catcher 33, with the result that the lower catcher will be moved into its gripping position in advance of the upper catcher being moved into its gripping position. Therefore, when the lower catcher 3| is functioning eciently, this catcher will be engaged with the core and will function to break off said core. Under such a condition, the upper catcher 33 remains inactive and the core will be recovered as the assembly is Withdrawn from the well bore. In the event that the lower catcher 3| should fail to operate for any reason, a continued upward movement of the drill pipe and outer barrel together with the inner barrel, with respect to the core, will cause the upper catcher 33 to enter the tapered actuating portion 34a of the bore of the extension 35 with the result that the resilient fingers of said upper catcher will be engaged with the core to break of! said core. Thus, the second core catcher provides a means which will assure recovery of the core in the event that the lower catcher 3l fails to function. However. so long as the lower catcher is operating properly, the upper catcher 33 remains inactive.

It may sometimes occur that the core bit I6 and the outer barrel I3 may become stuck or wedged within the well bore and an attempted upward movement of the drill pipe to withdraw the same cannot be accomplished. In such event, the coarse threads I2 of the special couplingl II may be utilized to disconnect the drill pipe I9 and coupling, as well as the inner barrel which is carried by said coupling, from the outer barrel I3 and the bit I4. I'he outer barrel and bit may thus be left in the well bore and the inner barrel, together with the core therein, recovered. The outer barrel may then be later fished from the well bore by means of the usual fishing tools.

The foregoing description of the invention is explanatory thereof and various changes in the size, shape and materials, as well as in the details of the illustrated construction may be made, within the scope of the appended claims. without departing from the spirit of the invention.

Having described the invention, I claim:

1. A coring apparatus including, an outer barrel, a core bit having an axial bore attached to the lower end of the barrel, an inner core-receiving barrel mounted axially within the outer barrel, a lower core catcher mounted within the bore of the core bit for axial movement upwardly relative to the outer barrel out of gripping engagement with a core extending therethrough and for axial downward movement relative to the outer barrel for gripping the core, the bore of said bit having an inclined seating surface adapted to coact with the outer surface of the lower core catcher upon relative movement of the bit and catcher for moving said catcher downwardly from nongripping to gripping position, a shoulder on said outer barrel for limiting the upward movement of said catcher with respect to its inclined actuating surface, whereby the amount of relative movement of the bit and catcher necessary to move the catcher into gripping position is controlled by the distance between said shoulder and said inclined surface, an upper core catcher within the outer surface of the bore of the inner barrel mounted for axial movement upwardly relative to the inner barrel out of gripping engagement with a core extending therethrough and for axial downward movement relative to the inner barrel for gripping the core, said bore having a tapered surface which is adapted to coact with the uppercatcher upon relative movement of the barrel and catcher for moving the upper catcher downwardly into gripping position, and a shoulder within the bore of the inner barrel engageable by the upper catcher and spaced a predetermined distance from the tapered actuating surface to control the amount of relative movement between the barrel and upper catcher which is required to move said catcher into gripping position.

2. A coring apparatus as set forth in claim 1, wherein the distance between the shoulder and inclined actuating surface of the lower catcher is less than the distance between the shoulder and tapered actuating surface of the upper catcher, whereby said lower catcher is operated and moved into gripping position upon a lesser relative movement of the apparatus with respect to the core than is required to operate the upper catcher.

3. A coring apparatus including, an outer barrel, a core bit having an ma bore attached to the lower end of the barrel, a lower radially expansible annularcore 'catcher mounted within the core drill and movable axially within limits therein, co-acting surfaces on said core catcher and within the bit for contracting the catcher into gripping position with the ocre or to permit expansion of said catcher to a non-gripping position with respect to the core, said co-acting surfaces being disposed to move the core catcher into gripping or non-gripping position in accordance with the relative axial movement of the core catcher in a predetermined position with respect to the bit, an upper radially expansible core catcher mounted within the core barrel and movable axially within limits therein, co-acting surfaces on said upper core catcher and within the barrel for contracting said upper core catcher into gripping position with the core or to permit expansion of said catcher to a non-gripping position with respect to the core, said co-acting surfaces on said upper core catcher and core barrel being disposed to move said upper core catcher into gripping or non-gripping position in accordance with the relative axial movement of the core barrel and upper core catcher, the core being cut being adapted to enter both upper and lower core catchers to frictionally engage said catchers to hold said catchers stationary whereby the axial movement of the core bit and core barrel relative to the catchers may be eiTected to move said catchers into gripping or non-gripping position in accordance with the direction of such axial movement.

4. A coring apparatus as set forth in claim 3, wherein the co-acting surfaces which actuate the core-catchers are inclined in a direction to permit expansion of the catchers when the bit and barrel are moved downwardly with respect to the core-catchers and which effects contraction of said catchers upon upward movement of the bit and barrel relative to said catchers. Y.

5. A coring apparatus as set forth in claim wherein the co-acting surfaces which actuate the core-catchers are inclined in a direction to permit expansion of the catchers when the bit and barrel are moved downwardly with respect to the core-catchers and which effects contraction of said catchers upon upward movement of the bit and barrel relative to said catchers, the co-acting surfaces which actuate the lower catcher being so located with respect to the co-acting surfaces which actuate the upper catcher that the lower catcher is moved into a core gripping position by a lesser relative movement of the bit with respect to said lower catcher than the relative movement of the core barrel with respect to the upper catcher which is necessary to move the upper catcher into core gripping position.

6. A coring apparatus including, an outer barrel, a core bit having an axial bore attached to the lower end of the barrel, an inner core-receiving barrel mounted axially within the outer barrel, a radially expansible lower core catcher mounted within the bore of the core bit and adapted to be moved into an expanded position out of gripping contact with the core as said core moves upwardly therethrough, the bore of said bit having an inclined seating surface adapted to engage the outer surface of and to coact with the core catcher upon relative movement of the catcher downwardly relative to the bit for moving said catcher from the expanded nongripping position with respect to the bore to a. position with said lower core catcher gripping the core, an upper core catcher mounted within the bore of the inner barrel, the bore of said barrel having an inclined surface which is adapted to coact with said upper core catcher upon relative longitudinal movement of the barrel and catcher for moving said upper catcher from nongripping to gripping positions with respect to the core, means connecting said barrel and said drill for longitudinal movement thereof together. and the position of the lower catcher with respect to its inclined actuating surface being such, as compared to the position of the upper catcher with respect to its inclined actuating surface, that said lower catcher is moved into gripping contact with the core in advance of the upper catcher being moved into its gripping contact with the core upon a longitudinal movement of said barrel and said drill relative to said core catchers, whereby said lower catcher will grip said core before the upper catcher is actuated.

JOHN C. STOKES.

References Cited in the flle of this patent UNITED STATES PATENTS Number Name Date 1,643,338 Halvorsen Sept. 27, 1927 2,019,176 Dodds Oct. 29, 1935 2,034,257 Hampton Mar. 17, 1936 2,040,889 Whinnen May 19, 1936 2,066,625 Howard et al. Jan. 5, 1937 2,189,923 Phipps Feb. 13, 1940 2,314,352 Hoffoss Mar. 23, 1943 2,326,908 Williams, Jr Aug. 17, 1943 

